Sorting conveyor systems 10 (FIG. 15) are known in the art to facilitate handling objects in settings such as warehouses, retail distribution centers, postal facilities, etc. These systems typically include a high speed main conveyor 12 that connects the individual stations where various functions are performed on the objects. In addition to an import station 22 where the objects are initially received and a dispatch station 14 where the objects are sent when shipped to the desired location, an exemplary sorting conveyor system may include a processing station 16, sorting station 18, storage station 20, etc. Typically, main conveyor 12 can handle many more objects than the conveyor systems present at the individual stations, as would be expected. For example, known sorting conveyors used by the United States Postal Service have main conveyors 12 that can handle 200 mail trays per minute, or more, whereas the existing pick and place automated storage and retrieval systems (ASRS) 20 for temporarily storing the trays may only be able to handle the storage and retrieval of as few as three trays per minute. The limiting factor for the number of trays the existing ASRSs can handle is generally the inability of the system's robot to place or retrieve multiple objects simultaneously. As such, multiple ASRSs are typically required to help prevent backing up trays on the main conveyor as they wait to be stored.
Additionally, known cross transfers that are used to move objects from one conveyor transversely to another conveyor at their intersection are known to cause issues with reliable conveyance. More specifically, one known type of cross transfer uses pluralities of rotating belts that are disposed between and below rollers of a conveyor. When it is desired to move an object from the initial conveyor to a subsequent conveyor, the belt assembly is raised above the rollers of the initial conveyor where they frictionally engage the bottom surface of the object being transferred. In those instances where the bottom surface is not flat or the object has uneven weight distribution, the object may become skewed as each belt of the cross transfer does not equally engage and, therefore, propel the object. As expected, skewing of the conveyed objects can lead to reduced operating speeds and even jamming of the conveyors.
The present invention recognizes and addresses considerations of prior art constructions and methods.